definitions of hardcore music are widely different, so this definition is meant as a guide. hardcore did originally grow out of punk somwhere along the line in the 80's. and when i say punk, i mean punk in the ballpark of the Misfits. it began to stand on its own in the early 90's with a few pioneering bands. these early bands were very unpolished, but people looking for the heaviest sound possible became the first fans. throughout the 90's, the line between hardcore and metal thinned, because at the same time some metal bands were also finding a heavier sound.
now skip ahead to the present. at this point, that heavy metal/90's hardcore gap has been closed. however there is a new barrier. everything changed when bands like Terror, Hoods, and Madball started hitting the scene (for lack of a better word). there is no denying the difference between Terror and Unearth. now that awful term "metalcore" has come about. Unearth leans sounds sort of hardcore, but they are metal. Terror is 'straight up' hardcore. kids who listen to Terror know that what they listen to is heavier than what Unearth kids listen to. so as far as they're concerned, Unearth IS NOT hardcore. so now there is 'hardcore' and there is 'real hardcore' or 'straight up hardcore'. THERE IS A DEFINATE DIFFERENCE BETWEEN THE TWO STYLES OF MUSIC.
most fans of 'straight up hardcore' accept and like 'hardcore' music, but dont like it being called hardcore. and they dont like 'hardcore' kids trying to act tough, because they know the music they listen to is tougher. so as much as i am against terms like "metalcore" it is probably a good idea to start using them because of the difference between the metal side and hardcore side.
there is no 'hardcorest' music, just hardcore. if something more hardcore comes along, then that becomes the definition of hardcore. thats why bands like Terror are taking the term for themselves with little opposition; because they are right to. when critics hail their album saying "this is what hardcore is supposed to sound like" there is little arguing that its for real.

Zao (most metal side of what is called hardcore)
Unearth (a blend of hardcore and metal that leans very much on the metal side)
Remembering Never (a blend of hardcore and metal that leans very much on the hardcore side)
Terror (doesnt get more hardcore than this)

A variety of punk rock originating in the US in the early '80s. It involves shouted vocals (as opposed to growled) with a fast, aggressive tempo and a guitar sound featuring quick chord changes. Minor Threat, Bad Brains, SSD, and the Circle Jerks are known for this style. By 1986, a new style of hardcore came out of the New York scene. The NYHC scene added mosh breakdowns to mix, but the music retained its fast aggressive nature. This spawned the youth crew scene, a positive straight edge scene featuring such bands as Youth of Today, Chain of Strength, and the Gorilla Biscuits. Judge is a notable band from this era that added some metal style to their riffs. In the 90s hardcore took many different direction, bands like Lifetime and Turning Point took the late '80s sound (particularly the melodic approach pioneered by the Gorilla Biscuits) and added a softer sung vocals and the lyrical approach of DC bands like the Rites of Spring and Dag Nasty. Other bands like Earth Crisis mixed hardcore with death metal growls and slow brutal guitars. Today many bands continue to play the early '80s fast, thrashy style as well as the so-called '88 or youth crew style, while still others have taken the sound of bands like Earth Crisis farther and mixed in more metal elements such as double bass drumming. Hardcore refers to all of these styles, though metalcore is best used to identify bands like Throwdown or Converge (who don't really sound anything alike but both mix metal and hardcore). Finally, some bands like Bane, With Honor, and Comeback Kid are mixing positive youth crew style hardcore with more complex metal riffing without straying into the beatdown, double bass drumming style of metalcore. People talking about old-school hardcore should be referring to one of the hardcore sounds that developed in the '80s, regardless of when the band formed.

in the music sense, a form of underground music that takes music to extremes. started in the early 80`s with bands like minor threat and black flag. i like to call this classic hardcore. then in the late 80`s there were many hardline, "positive" straightedge bands like chain of strength and gorilla biscuits. i like to call this oldchool hardcore. then in the early 90`s straigtedge became rediculous, and the bands got more metallic, with bands like Earth Crisis and Strife. I just call this hardcore. Then all throughout the 90s there were those hardcore bands with the scary, grindy sound, like converge, dillenger escape plan, or discordence axis. Then there were some bands like 10 yard fight who tried to re-create the hardcore sound of the late 80`s, a few were ok but most really sucked. This developed into what some people call "posi" hardcore. These days, you have your choice of shitty mosh hardcore, or screamo, or emo-core. Now hardcore is just a melting pot of all the sounds in one. its one big emotional, positive/negative, noisy vomit. its ok i guess. i liked how it was better in the late 90s early 00s.

A subgenre of electronic music characterized by fast, hard basslines and often making use of turntablism or an MC for live performances. This is used often as an umbrella term to describe happy hardcore, gabber, speedcore, upfront, or any of the many related hardcore genres.

An adjacetive used to describe a person who is indominatable of will. This person can and will sustain serious, possibly life-threatening injuries as a matter of course in daily life, and then will continue to tredge on as if unscathed, inflicting incredulous amounts of pain on those that get in his/her way. A hardcore person refuses to give up, no matter the odds, or the situation, which can sometimes lead to people thinking the person "stupid." To truly be hardcore one must display wounds and/or scars as if they were medals of honor and constantly impart the amazing stories that accompany such medals with great enthusiasm. This word should only be used to describe the manliest of men.

Jesus man, Dave is so hardcore...Look, he's bleeding out of his eye and he isn't coming out of the game..."